Website false mobile detect

Apparently, this is starting to happen all over. On one website (bcbsm.com - Blue Cross Blue Shield of Michigan) ... everyone can get there fine (if they care) and the main home page shows up ... except for one desktop PC ... when it goes there, it tries to redirect to their mobile page...although the screen remains blank. It does this on IE9 and Firefox and Chrome. The noscript in Firefox will stop the redirection, but you are still nowhere with a blank screen. The help desk at bcbsm is scratching their head. The user has no problems at other sites. I tried one fix, which was to type in, in their case, www.bcbsm.com/index.shtml , but that just goes to their equivalent of a 404 error screen and very helpfully gives you a link to the main screen where the redirection happens again. What is it on that PC that their script might be looking at to falsely determine that the desktop is a mobile device? Haven't found any real help on this searching the web.